1. Technical Field
The present invention relates to a manufacturing method for a semiconductor memory device formed by a plurality of memory cells in an FET structure, and to a remanufacturing method and reshipping method for such a semiconductor memory device.
2. Description of the Related Art
As a memory device not requiring power in holding information data, there is a non-volatile semiconductor memory device having a plurality of memory cells in an FET structure (in a field-effect transistor structure with a source, a gate and a drain) with using the charge traps in its insulation film for charge storage. For example, see Japanese Patent Kokai No. 2005-64295 (patent document 1). In the non-volatile semiconductor memory device like this, its charge hold characteristic deteriorates due to the repeated writing and erasure of information data. In addition, disturbance is readily undergone upon writing information data. Disturbance refers to the influence that a certain memory cell is to suffer when writing information data to another memory cell. For this reason, the information data is practically not rewritten for the non-volatile semiconductor memory after once being written with information data. Such a non-volatile semiconductor memory, whose information data after written is not to be rewritten, is utilized as a memory device for storing a program. In some cases, program rewriting is desirably not allowed. The non-volatile semiconductor memory device, structured not to rewrite information data after once being written with information data, is capable of preventing its program from being falsified and hence suited as a memory device for storing a program.